Window guide channels, variously known as window channels, window glass channels, glass run channels, glass runs, guide-ways for sliding windows and window guides, are disclosed in McKinney U.S. Pat. No. 1,876,519; Bailey U.S. Pat. No. 1,903,541; Reid U.S. Pat. No. 1,967,514; Reid U.S. Pat. No. 2,041,956; Hoffman U.S. Pat. No. 2,058,793; Cameron U.S. Pat. No. 2,399,204; Mesnel U.S. Pat. No. 2,407,671; Bascom U.S. Pat. No. 2,412,796; Anderson U.S. Pat. No. 2,474,409; McKinney U.S. Pat. No. 2,635,915; Merrill U.S. Pat. No. 2,728,982 and Bright U.S. Pat. No. 2,933,342.
Such guide channels usually comprise a sheet metal core of sufficient rigidity for proper lateral support of the window received thereby and a flexible covering of woven fabric, rubber, plastic or other suitable material for said core.
In the Merrill patent for example, a sheet metal strip is disclosed having spaced elongated transverse indentations formed in the strip which extends from the edges of the strip toward the center at right angles to the edges and having slits intermediate the indentations and parallel thereto, to thereby provide tongues between the slits, the tongues containing the indentations.
The indentations do not extend across the central or median area of the strip, so that when the strip is bent or formed into channel-shaped form to provide a core reinforcement for the guide channel, the indentations add little or nothing to the strength or rigidity of the core.
Moreover, the fact that the tongues are in direct abutment with each other at the slits, prevents the strip from being bent or curved longitudinally to accommodate the strip to curvatures at the window corners.